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HANDBOOK OF PHYSIOLOGY 



NEUROPHYSIOLOGY I 



FIG. 13. Volta and the experiment cf Galvani that led to the development of the Voltaic pile. 

 The engraving of Volta is from the drawing by Roberto Focasi. Volta was an admirer of and was 

 honored by Napoleon, one of whose gestures he seems to have caught. Behind him is a Voltaic pile. 

 The sketch at the right was composed by an artist from a drawing made by du Bois-Rcymond when 

 he visited Galvani's house 54 years after the latter's death. It depicts the experiment (designed to 

 test atmospheric electricity) in which Galvani stumbled on the phenomenon of bimetallic electricity. 

 (From Reden von Emit du Bois-Reymond, 1887, vol. 2.) 



to complete the circuit. If thi.s third material were a 

 frog's muscle, it would by \irtue of its irritability react 

 to the flow of bimetallic electricity, but its role (ac- 

 cording to Volta) was solely that of an electroscope 

 (75). When Aldini (76) demonstrated by dipping 

 ends of nerve and muscle in mercury that the same 

 effect could be obtained with a single metal, Volta 

 replied that the .surface in contact with the air 

 suffered a change that made it heterogeneous with 

 the depth. This tortuous argument was disproved by 

 von Humboldt (77). 



Before Galvani's death an anonymous (78) tract 

 was published, almost certainly with his collaboration, 

 in which an experiment was described on the twitch- 

 ing of muscles in the absence of any metals or external 



75. Volta, Alessandro (1745-1827). On electricity e.xcited 

 by the mere contact of conducting substances of different 

 kinds. Phil. Trans, go: 403, 1800. 



76. Aldini, Giovanni (1762- 1834). De animali Electricitate 

 dissertationes dime. Bologna, 1794. 



77. VON Humboldt, Frederick Alexander (1769-1859). Ver- 

 suche iiber die gereizle Muskel- und .Nervenjasser. Posen und 

 Berlin, 1797. 



78. Anonymous. Dell'uso e dell' attivita dell'Arco condultore nelle 

 contrazioni del muscoli. With Supplemento. Bologna: S. 

 Tommaso Aquino, 1 794; part of the Supplemento has 

 been translated into English by M. Tschou in: B. Dibner. 

 Galvani-Volta. Nor walk: Burndy Library, 1952. 



source of electricity. A contraction was demonstrated 

 when the cut end of a frog's spine fell over onto its 

 muscle or when one limb was drawn up to touch the 

 exposed sciatic nerve (see fig. 12). In this case the 

 source of electricity was what we now recognize as 

 the current of injury. Even after this demonstration 

 (79) Volta tried to explain the current flow as the re- 

 sult of heterogeneity of tissues (muscle and nerve). 



The design of Humboldt's experiments and the 

 clarity of his reasoning are a pleasure to study in 

 the welter of acrimonious controversy that greeted 

 GaKani's findings. Without bias towards either 

 protagonist Humboldt repeated their experiments, 

 examined their interpretations, designed new experi- 

 ments to test their hypotheses and came to the con- 

 clusion that Galvani uncovered two genuine phe- 

 nomena (bimetallic electricity and intrin.sic animal 

 electricity) and that the.se were not mutually exclu- 

 sive. Humboldt demonstrated that both great scientists 

 erred in their interpretations of their experiments; 

 however, from these were to grow the science of 

 electrophysiology on the one hand and, on the other, 

 the brilliant development of the electric battery. Not 

 only does Humboldt expose the erroneous parts of 

 Galvani's and of Volta's interpretations but also 



79. Volta, .\. Phil. Mag. 4: 163, 1799. 



